Tsumiki is a young girl with brown eyes and brown hair. Her long hair is styled in a ponytail and keeps long bangs on both sides of her face.
While in middle school, Tsumiki wore a school uniform that consisted of a tan colored jacket with a black edge over a white colored button shirt and a red tie, navy skirt, black stockings, and black shoes.
Tsumiki has been shown to wear a light colored turtleneck under a pink cardigan.
Tsumiki is a kind girl who cared deeply for her step-brother Megumi and would often times scold him for getting himself into many fights.
When Tsumiki was in elementary school, her mother married Toji Fushiguro and she subsequently joined by Toji's son, Megumi. Their parent later disappeared without a trace. She studied at Saitama Urami East Junior High along with her brother. Tsumiki would check up on her brother since he would often get into many fights. While in her third year at Saitama Urami East Junior High, she along with two classmates went to Yasohachi Bridge one night. Tsumiki was cursed, and fell into coma, along with other victims across the country. 
During an investigation at Yasohachi Bridge, Megumi finds out that Tsumiki might be connected to the investigation. Megumi contacts Kiyotaka Ijichi to check on his sister, which Kiyotaka informs Megumi about how his sister is in the same condition as she was before.
As said by Pseudo-Geto he had already marked Tsumiki prior to the events at Shibuya and now casted Idle Transfiguration on her and another person in which he said one who had consumed a cursed object like Yuji and the other had been "marked with cursed energy whose brains were meant to be that of non-sorcerers' like Junpei. To the former he gave strength as vessels and to the latter he gave the capacity to use cursed techniques. He then proceeds to break the seal binding them and says to some they have been in deep sleep as this is the case with Tsumiki and in order for them to deeply understand cursed energy they will soon awaken and fight against each other.
Abilities and Powers
Currently, nothing is known about her abilities.
- Tsumiki's surname contains the kanji for "bend down, bow" (伏 fushi?) and "black" (黒 guro?), and her first name contains "port, harbor" (津 tsu?), "beautiful" (美 mi?) and "chronicle" (紀 ki?).